Thrust bearing lubricant measurement and balance

ABSTRACT

A method of determining the axial thrust on a thrust bearing assembly having a fixed and a rotating component in which a lubricant is being forced between the mated faces of the respective components and where zones of pressure are built up during operation, comprising monitoring the pressure of the lubricant between the mated faces. The invention also provides for determining the axial thrust by measuring the pressure differential of the lubricant between the mated faces or as it enters therebetween and as it emerges from between said faces. To measure the axial thrust on a pair of opposing thrust bearing assemblies, the pressure differential of the lubricant between the respective mated faces of the two assemblies is obtained. The axial thrust measurement can be utilized in a method of adjusting the axial thrust on the bearing assemblies by changing manually or automatically a balancing apparatus separate from the thrust bearings and their lubricant and used to adjust the net thrust on the bearings in response to the respective pressure measurement. The invention also encompasses the combination of suitable pressure measuring devices with thrust bearing assemblies with balancing apparatus to carry out the above measurement and control methods.

United States Patent [191 Swearingen 1 July 22, 1975 THRUST BEARINGLUBRICANT I MEASUREMENT AND BALANCE Judson S. Swearingen, 500 Bel AirRd., Los Angeles, Calif. 90024 22 Filed: Sept. 7, 1973 211' Appl. No.:395,246

Related U.S. Application Data [76] Inventor:

52 us. Cl. l84/6.4; 415/104; 184/6.16;

308/9 [51] Int. Cl. ..F01m 1/18 [58] Field of Search 184/6 R, 6.4, 1 E,6.16;

415/104, 105, 106, 112, 131; 308/9, DIG. 1; 73/140, 141 R; 277/3, 15

Primary Examiner-Richard C. Pinkham Assistant Examiner-Marvin SiskindAttorney, Agent, or FirmBrowning & Bushman 57 I ABSTRACT A method ofdetermining the axial thrust on a thrust bearing assembly having a fixedand a rotating compo nent in which a lubricant is being forced betweenthe mated faces of the respective components and where zones of pressureare built up during operation. comprising monitoring the pressure of thelubricant between the mated faces. The invention also provides fordetermining the axial thrust by measuring the pressure differential ofthe lubricant between the mated faces or as it enters therebetween andas it emerges from between said faces. To measure the axial thrust on apair of opposing thrust bearing assemblies, the pressure differential ofthe lubricant between the respective mated faces of the two assembliesis obtained. The axial thrust measurement can be utilized in a method ofadjusting the axial thrust on the bearing assemblies by changingmanually or automatically a balancing apparatus separate from the thrustbearings and their lubricant and used to adjust the net thrust on thebearings in response to the respective pressure measurement. Theinvention also encompasses the combination of suitable pressuremeasuring devices with thrust bearing assemblies with balancing apparatus to carry out the above measurement and control methods.

13 Claims, 10 Drawing Figures FILTER PATENTEDJUL 22 ms SHEET EMCHIKPATENTEDJUL 22 ms QN NM QQQU \N wmknik MI I PATENTED JUL 2 2 ms SHEETnow U.S. Pat. No. 3.828.610.

THRUST BEARING LUBRICANT MEASUREMENT AND BALANCE BACKGROUND OF THEINVENTION This application is a continuation in part of my earliercopending application, Ser. No. L130 filed Jan. 7. 1970 and nowabandoned, and also of my copending application, Ser. No. 210,705 filedDec. 22, 1971 and The present invention relates to rotating machinerywhich may be subject to axial thrust loading. More par .ticularly theinvention relates to the measurement and control of axial thrust onthrust bearing assemblies.

In high speed rotating machinery such as centrifugal pumps, compressors,turbines, turboexpanders and the like, many of the maintenance problemsoriginate in the thrust bearings primarily due to the fact that thethrust on the shaft is subject to wide variations due to many factors,among which are pressure or load variations on the machinery, poor sealdesign, etc. Unlike journal bearings which are circumferential, thrustbearings are radial and should the lubrication fail momentarily,centrifugal force acts to sling out the residual lubricating oil andquickly permits metal-to-metal contact of the bearing faces.Furthermore, thrust bear- -ings have much higher rubbing speeds than theassociated journal bearings. In many pieces of rotating machinery suchas those mentioned above. in order to minimize thrust bearing failureproblems, the thrust on the shaft is calculated and than a balancingmeans provided which acts to supposedly neutralize the calculated thrustor at least bring it within a small selected range. For example, inmultistage machines such as turbine compressors, turboexpanders, and thelike so called balancing drums" are used. Unfortunately, unless thethrust load is known, the balancing means is of minimal value. In anyevent, since thrust load is not easily estimated in many cases or maychange very rapidly from its supposed known" value, the use of abalancing means may not always prove to be satisfactory. Heretofore, noeasy or accurate methods of measuring thrust load have been availablewhich would permit maximum utilization of a balancing means.

SUMMARY OF THE INVENTION It is therefore an object of the presentinvention to provide a method for determining the axial thrust on athrust bearing assembly.

Another object of the present invention is to provide a method formeasuring the axial thrust on a pair of op posing thrust bearings usedto maintain axial position of a shaft.

Yet another object of the present invention is to provide a method forcontrolling the axial thrust on a thrust bearing assembly.

Still another object of the present invention is to provide a method forcontrolling the axial thrust on a pair of opposing thrust bearings usedto maintain axial location of a shaft.

Another object of the present invention is to provide a suitablemeasuring device in combination with a bearing assembly for measuringthe axial thrust on the bearing assembly.

A further object of the present invention is to provide a system wherebythe axial thrust on bearing assemblies may be controlled automatically.

These and other objects of the present invention will given herein andthe appended claims.

In a typical thrust bearing assembly there is a rotating componentattached to the shaft and a fixed component through which the shaftextends. Opposed faces. one on each of the components, are generallymated together to form the thrust bearing surface. Common practice callsfor injecting a lubricant through the fixed component and then allowingit to flow radially outward away therefrom between the mated faces ofsuch fixed and rotating components. One of the common designs of themated bearing faces is such that a resistance to the radial flow of thelubricant between the mated faces exists and the axial thrust beingexerted on the bearing can be determined by monitoring the pressurebetween the mated faces or the pressure gradient of the lubricant acrossthe mated faces of the bearing assembly. The pressure gradientmeasurement can be made entirely between the mated faces or by sensingthe difference between the pressure between the mated faces and areference pressure external ofthe bearing or between the mated faces ofanother bearing.

In the case of opposing thrust bearings of this kind used to axiallyposition a shaft. the determination of ,axial thrust can be accomplishedby measuring the pressure differential of the lubricant existing betweenthe respective mated faces of the bearing assemblies.

The axial thrust measurement can be made the basis of a method forcontrolling axial thrust by using the various pressure measurements as abasis for adjusting a balancing means or other such device used tocontrol the net axial thrust on a thrust hearing.

In another aspect. the present invention contemplates the combination ofa thrust bearing assembly with suitable pressure measuring devicesconnected so as to carry out the above-described pressure measurementsand the further combination with a balancing device or other such meansto control, either automatically or manually. the axial thrust on thethrust bearings.

There are other types of thrust bearings which may not have significantlubricant pressure drop between inlet and discharge points which dependupon such features for carrying load as fixed tapered shoes, fixed stepshoes (Raleigh bearing), spiral groove (Whipped) bearings, tilting shoe(Kingsbury) bearings, cone-seat bearings and the like. However, the loadis supported in all cases by pressure buildup, and a conduit connectingone of these areas to a pressure-measuring means will respond to thesupport load and the present invention can thus apply to them as well.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view, partly in section.of one embodiment of the presenet invention, employing thrust bearingsof the type having significant pressure drop between inlet and dischargepoints and illustrating the use of the pressure of lubricant within eachof two opposed bearings as references for each other. together with theautomatic control of thrust in accordance with variation in differentialbetween pressure within a bearing and a reference pressure.

FIG. 2 is a fragmentary view similar to the right hand portion of FIG. 1illustrating another embodiment of the present invention applied to thesame type of bearmg.

FIGJ3 is a view similar to'FIG. 2 illustrating yet another embodiment ofthe present invention applied to the same type of bearing."

f i FIG. 4 is a fragmentary view'similar to'a portion of FIG. 2 showingthe application of this invention' ti'v a fixed shoe bearing as above'mentioncd. g

FIG. 5 is a fragmentary view showing the faces of the fixed shoes of thebearing of FIG. 4, taken along 'the line 55 of FIG. 4. i 1

FIG. 6 is a fragmentary sectional view along the line 66 of FIG. 5showing the circumferential profile of such shoes to be of the fixedtapered"var iety.

FIG. 7 is a view similar to FIG. 6 but showing what the circumferentialprofile of the fixed step or Ra- DESCRIPTION, OF THE PREFERRED 1- IEMBODIMENTS Referring now to FIG. I, there is shown generally acentrifugal compressor 10. Compressor shaft 11 is ro tatably mounted injournal bearings 12 and 13, one face l4a or a of each representing anyof the various types of thrust bearings mentioned above and mated toa-plari' face of rotating disc-shaped thrust bearing members 14 and 15,respectively, which are fixedly mounted on shaft ll."The bearingassemblies comprising j ournal bearings l2 and I3 and thrust bearings 14and 15' are lubricated through lubrication ports I6 and 17 which extendthrough journal bearings 12 and 13 and'intothe journal bearing spaces12a and'l3a between shaft 11 and journal bearingsl2 and l 3.Lubricating'oil drawn fr'om reservoir 18 is circulated via pump19,"coo1er 20, "filter 21, and pressure regulator 21a, then through flowlimiting orifices22 and 23 and then into lubrication pol ts' l6 and '17.Lubricating oil forced into journal bearing spaces 12a and 13d willflowfax'ially along shaft 11, a portion entering thrust bearing spaces24 and 25 between the mated faces fo the bearing assemblies and flowingradially outward between 'said' faces eventually escaping into bearingchamber 1121 where it drains through drain tap 115 into concliiit 11cand into reservoir 18. As previously stated, the r at'e'oflubricant flowis limited by orifices 22 and 23.'Usu'ally section 1211 and 13b of therespective bearings are of such clearance as to be restrictive and theywill replace the said orifices. The-mated bearing faces also containrestrictions 26 and 27 at their discharge edges to prevent massive lossof lubricating oil from the Bearing'assemblies. As shown, therestrictionsconsist of lips 26 and 27 which extend'around thecircumference of the thrust bearing faces of journal bearings 12'and"l3.' Referring to just oneiof the bearing assemblies,

tance to flow of lubricant between lip 26 and thrust bearing'l4 andresult in a buildup of pressure oflu b ricant in' space 241 The pressuredistribution is not n'ecesfn sarily uniform depending upon the tpe ofbearing, but one versed in the art will know where the pressure 4builduri io ne is so to favorably locate pressure taps 28 and29. Therise in pressu're in space 24 will tend to urge thrust bearing awayfrom, the thrust face of journal bearing 12 until the clearance betweenlip 26 and thrust bearing l4is adjusted'so as to control said pressurein 24 'at a point where the thrust load issupported. Since as shown inFIG. 1', there are a pair of opposing thrust bearing assemblies tomaintain the axial position of shaft 11, a like measurement as describedfor thrust bearing 14 Cari be" made with respect to thrust bearing 15through pressure tap 29. If the lubricant flow entering the 're speetive.:bearing assemblies through orifices '22 and 23 is 'ess entiallythe same, anyaxial shifting of shaft 11 'will be evidenced y pressurechanges in thrust bearing spaces 24 and Z SQFOr example, irshan shiftstoward journal bearings 12, the pressure in 'space 24"willincreaseirelative to that in space 25. Consequently, the measurement ofthe pressure differential between thrustbearing space 24 and 25, whichcan be accomplished'by differential pressure measuring device'30,'co'nneeted to pressure taps 28 and 29 will give a direct indication ofthe axial tlirust loading on shaft 111 reflected in the different axialthrust being carried by the opposing bearing assemblies. v i i 'It willbe understood that even though the'thru st bearing assemblies areopposed, i.e., directed so that one assembly take's thejthrust of shaftmovement in one direction and the other assembly takes the thrust ofmovement of the shaft in the other direction, such as,- semblies areusually constructed with sufficient clear,- ance in the bearing spaces24 and 25 that they, do not Wo'rkagainst each other For example, if'theshaft 11 moves to the right, the assembly including bearing 14 is loadedas described above so that it takes the thrust of thismovement. At thesame time, such movement to the right causes the bearing assemblyincludingbearing 15 to be unloaded. Similarly, if the shaft moves totheleft, bearing 15 isloadeid and bearing 14 is unloaded. The pressure dropin the unloaded bearing is, for prac tieal purposes, fsimultaneous with.the initiation of movement of the shaft in the appropriate direction,Thus the unloaded bearing'provides an excellent reference pressurefortheloaded hearing. In "many instances a reference pressure in theunloaded one of apair of bearing assemblies is preferable to otheravailable referencepressures. For example, since. the reference pressureislo cated within the machine housingand is within a bearing which isunder zero thrust load, the pressure differential corresponding. tothrust of a given magnitude will accurately represent the pressuredue toloading of the loaded bearingin excess of pressure representing zeroload within a similar bearing. 7

i To illustrate the present invention with reference to a single bearingassembly, reference is made to FIG. 2 wherein only a portion ofthesystem set forth in FIG. 1 is shown. By connectingpressure measuringdevice 30a to pressure tap 28 and the monitoring the pressure of thelubricant in..the space 24, it is possible toascertain the axial thrustloading on the singlev bearing assembly since if the pressure over aperiod of time in space 24 decreases, it will be obvious that the thrustbearing 14 has shifted away,from-journalbearing 12 whereas if thepressure increases, it will be obvious that the thrust bearing 14 hasshifted towards journal bearing 12. Obviously, an identical measurementcan also be made on an opposing thrust bearing assembly and the twomeasurements compared if such is desired.

As explained above, when the resistance to flow of the lubricant frombetween the mated bearing faces is increased by shifting of the thrustbearing towards the thrust bearing face of the journal bearing, thepressure in the thrust bearing face'begins to build up, such that the rewill be a gradient in pressure of the lubricant radilubrication conduit16, so as to lift the bearing 14 or 15 away from the facing surface ofmember 12 or 13, then in order to determine the pressure differenceexisting between the mated faces, it is only necessary to take thedifference in the constant pressure reading and the pressure between themated bearing faces as determined using the arrangement of FIG. 2.

The bearing design shown in FIGS. 1 and 2 is schematic as well aspractical. In the schematic aspect it is intended to show therelationship of bearing load to the pressure in a pressurized zone inthe bearing.

Many, if not most, thrust bearings generate pressurized areas within thethrust-carrying zone by hydrodynamic action. The lubricant is dragged bythe rotating member into areas from which escape is restricted by theproximity of the mating thrust face. The total summation of incrementalpressure areas built-up in such zones is equal to the thrust load(within the bearings load-carrying capability). The pressuredistribution is substantially invariant with varying load except as tomagnitude and therefore a pressure measurement in any such pressurizedzone will give a good indication of the total thrust load.

Thus the configuration depicted in FIGS. 1 and 2, has a lubricantflow-limiting restriction as at 120 or 13b or 22-or 23 and a pressurecontaining restriction consisting of lip:26.*and 27 to produce a thrustload indicating (and carrying.) pressure zone between the mating thrustfaces. A pressure containing restriction is also present inthe designsshown in FIGS. 4 and 5, also in FIGS. 9 and 1 0.

In FIGS. 5 and 7 the lubricant is introduced into cond-uitgrooves 124and 125 which supply tapered areas 124a of FIG. 5 and fixed step grooves127 of FIG. 7. Thesetapered and fixed step areas by the drag action ofthemoving mating face build up pressure toward their down-stream endsbecause of the restricted escape passages from there. However, it is notnecessary to maintain special pressurization in grooves 124 and 125,only to provide a flooding supply of lubricant to the inlets to thetapered and the stepped zones. Thus, these grooves need not be closed asat 126, and may open as illustrated by the groove 126b, also asillustrated by FIG. 8 where the tilting shoes are flooded but notnecessarily pressurized by the lubricant stream.

Returning now to FIG. 1, it is seen that compressor 10 comprises animpeller 31 mounted on shaft 11 and rotating therewith. The fluid to becompressed enters at compressor inlet-'32 and is discharged atcompressor outlet 33 after passing radially outward through passages 34is impeller 31, the compressed fluid collecting in passage 35 beforebeing discharged through outlet 33. A large part of pressure rise in thefluid being compressed in attained as the fluid passes through impellerpassages 34 such that the pressuee of the fluid in passgae 35 is muchgreater than in inlet 32. The high pressusre existing in passage 35 islargely communicated into spacing 36 between the front face of impeller31 and the body of compressor 10. This spacing-is closed at its insideborder by the presence oflabyrinth seal 38. It leaks a small amount ofthe fluid from spacing 36 and returns it to suction via inlet 32. Thissmall leakage, which is of the order of a few percent of the total flow,has negligible effect on the system.

Similarly, the high pressure in passage 35 is also largely communicatedinto space 37 between the backside of impeller 31 and compressor body10. Likewise, labyrinth seal39 prevents all but a negligible leakage offluid into space 40, insofar as the performance of the compressor isconcerned; nonetheless the amount of leakage through labyrinth seal 39via clear ance 37 poses a significant problem because of the fact thatonce it enters space 40 between the backside ofv impeller 31 and thebody of compressor 10, it becomes impressed over the area of thebackside of impeller 31 area on the opposite side within seal 38 is notpressurized to offset it.

To overcome the above thrust problem, it is conventional, in high speedrotating machinery of the type described herein to provide some sort ofbalancing system whereby this thrust can be offset and thereby preventserious damageto the bearings. One common thrust balancing arrangementis seen in FIG. 1. A passageway 41 leads from clearance 40 to conduit 42thorugh valve 43 and then into passageway 44 which leads back to thesuction of inlet 32 of compressor 10. In conventional systemsemployingthis balancing system, valve 43 is absent and thus the fluidbeing compressed which is forced into clearance 40 is allowed to bleedback to the suction of inlet 32. Unfortunately, this balancing schemepresents certain complications inasmuch as the rate of leakage into andconsequently the pressure in, clearances 36' and 37 may vary dependingon the roughness in those passages and depending on the leak age rate ofseal 39. Moreover, there is a thrustdue to the impact of the fluidentering the compressor itself and it is very possible that there areother thrust influences acting on the rotating system. Therefore, themere drainage of the fluid out of clearance 40 and back into inlet 32via passageway 41, conduit 42, and passageway 44 may not prove to besatisfactory as a method of balancing the axial thrust. The inventionherein overcomes the problems associated with blindly attempting tobalance the thrust. If the thrust is toward the shaft and away from theinlet of impeller 31, then it is obvious that the pressure in chamber 40is lower than it should be or in other words, that the fluid is beingallowed to bleed back too freely into inlet 32. In order to overcomethis problem, I introduce valve 43, which can be closed slightly torestrict the flow of fluid out of chamber 40, thus maintaining thepressure in chamber 40 high enough to move impeller 31 in a directionaway from shaft 12. Again, if the pressure in chamber 40 is lower thanit should be with the result small" in space 25 will fall. This changein. the relative pressuresof the two chambers will=be immediately sensedby pressure differential device 30. By making pressure differentialdevice 30 a differential pressure .readersystem. 1

One particularly simple and advantageous'wayof automatically adjustingvalve 43 is by means of an actuating diaphragm. piston, or the like.Fluid from lines 28 and 29 can be directed to respective opposite sidesof thediaphragm or piston. The difference in the pressures would causeautomatic adjustment of the diaphragm or the like, and thus the valve43, in accord with the thrust load. It will be appreciated that thepressures in lines 28 and 29 would in most cases be sufficient tooperate such a diaphragm without amplification.

In the cases where the pressure gradient across the mated faces of abearing assemblyare being measured as depicted in FIG. 3, or if thechange in pressure betw.een thc mated faces of a bearing assembly isbeing monitored as depicted in FIG. 2, the thrust on the rotatingassembly can still be controlled by simplyadjusting valve 43 in responseto the reading of differential pres; sure measuring device 3012 orpressure gauge.30a This adjustmentcan be carried out manually oras wassaid for the arrangement depicted in FIG. 1, pressure devices 3Ila and3017 can have incorporated thereinneontroller systems whereby valve 43may be actuated .auto.-.

matically depending on the pressure reading. Suitable controller systemsinclude any pneumatic, electrical or hydraulic servo system commonlyemployed in automatic control schemes as well as the actuatingdiaphragrn type described above in connection with the embodiment ofFIG. 1. Obviously, excessive thrust in either direction may be socontrolled, although this mayinvolve some adjustment in the radius ofthe seal As shown, the bearing assembly has a peripheral lip whichrestricts the flow of lubricant out of the assembly in proportion to thethrust load, the remaining portion of the bearing surfaces beingsubstantially flat. In some bearing assemblies, it is common to haveradial or spiral grooves in one of the two thrust faces as shown inFIGS. 4, 5, 6 and 7, and in FIGS. 9 and 10, respectively,

or to have inclined surface sections. milled into the other face asshown in FIG. 6, or these inclinedsurfaces may be pivoted as in aKingsburyv bearing as shown in FIG. 8, all. of which have pressurebuild-up areas as hereinbefore described. The invention has equalapplication to such bearing systems provided thepressure' connectioncommunicates with a zone where there is a pressure buildup in thebearing in response to thrust loads. a I I More specifically, in FIG. 4,the rotating thrust bearing member 114 is shown facing an opposingstationary thrust bearing structure on the wall 1 l2 whichprovides .8the journal bearing for the shaft 111. This wall has a lubrica'tionport116 extending into the journal bearing intermediateits ends; Lubricantentering this bearing flows in opposite directions along the shaft. Thatflowing to the left through space 11217 enters the inner ends of radialgrooves 124. in FIGS. 5 and 6 or in FIG. 7. These may be terminatedshort of the outerperiphcry of the thrust bearing surface as shown at126. Pressureand rate of flow of oil into the grooves 124 or 125 arenotcritical so long as they are kept full. On one side of each groovethe face of member l12is formed with afixed flat surface sloping ortapered from deep to shallow in the direction in which the bearing 114moves over it in rotation, as at 124a in FIG. 6, or of uniformdepression as at 127 in FIG. 7. In either case these ter minate short ofthe next groove 124 or 125 being separated from such next groove by ahand 1260 in FIGS. 5 and 6 and 12741 in FIG. 7.

Connecting tothe space between one of the fixed tapered flat surfaces124a and the bearing member 114 is a passageway 128 through the wall 112having a pressure gauge at its outer end for monitoring the pressure insaid space at its opening near the land 126a. A similar passageway 129is provided in the fixed step bearing of FIG. 7 for monitoring thepressure in the space overlying one of the surfaces 127.

The Kingsbury bearing shown in part in FIG. 8 is similar in constructionto the fixed surface bearings of FIGS. 4, 5, and 6 and of FIG. 7. It isshown in corelation with the same shaft 111 and rotary thrust bearingmember 114 fixed on the shaft as are the bearings in FIGS. 4, 5, 6.and7. In this case, however, the lubricant will be supplied to the bearingface of the thrust bearing member 114. by suitable means such aspermitting the member 1 l4 to pass at least approximately its lower halfthrough. an -oil bath as it rotates, or flooding the bearing shoes224with lubricant by other means. There are a number of such shoescircumferentially spaced from one an other and-corresponding roughly tothe spaces between the grooves 124 and 125 in FIGS. 6 and 7,respectively. However, each shoe is pivotally sepa-, rately mounted asat 226 on the stationarybearing wall 212. -Essentially such shoe must befree to pivot on an axis approximately radial relative to the axis ofshaft 111 but customarily it will be mountedforuniversal pivotalmovement. In operation it will assumeaposition such that its surfacefacing the bearing member 114 will approximate the tilted or inclineposition of surface 124a of FIG. 6, as will be later more fullydiscussed. Y l

For the purpose of monitoring the pressure betweenone of the shoes,; 224and the bearing member 114, a passageway.22 8 is provided through thewall 212, with a pressure gauge 130, connected to its outeraend.Itsinner end-is connected through one of the pivotal mountings 226 witha passageway 228a through the corresponding shoe.224 and opening throughthe face of that shoe which is opposed to bearing member 114.

Referring now to FIGS. 9 and 10,.the bearing shown employs a shaft 111and bearing member 114 which may be the same as those shown in FIGS. 4through 8. Lubricant may be supplied by a passageway 316 through astationary bearing support wall 312 opening at its inner end into aradial bearing 312b, from which part flows through such bearing alongshaft 111 and its outer end, to a connection to a pressure gauge 130, bywhich the pressure between the bearing faces within one of the groovesmay be monitored.

The bearings, per se, of FIGS. 4 through 10, all of which have beenknown long prior to this invention,

differ in operation from those of FIGS. 1 3 in the way in which the oilpressure, between the rotating and stationary faces-of the thrustbearing is built up. All operate by providing a pressurized body of oilbetween such faces to transmit the thrust forces between them and allprovide a pressure in such body which varies proportional to the totalthrust so transmitted. The present invention monitors such total thrustby monitoring the pressures in the respective pressurized bodies of oil.

However, the pressure in FIGS. 1 3 is generated by the thrust forcetending to close the outlet from such body of oil between the lip 26 or27 and the adjacent facing surface of member 14 or while oil continuesto be fed into the body. Thus the pressure is actually varied inaccordance with and proportional to endwise movement of the shaft andthe maintenance of pressure indicative of the degree of thrust isdependent on maintenance of a rate and pressure of inflow sufficient tokeep the lip 26 or 27 separated from member 14 or 15. It will operatewhether or not there is rotation and may be said to be a hydrostatictype of bearing.

The forms shown in FIGS. 4 l0 depend on rotation to provide the pressureof oil between the thrust hear ing parts and may be termed hydrodynamicbearings. In FIGS. 4 6 rotation of the bearing member 114 across thegrooves 124 sweeps oil from the grooves up and along the inclined ortapered surfaces 124a and builds it up thereon unitl the pressuretherein is sufficient to begin to separate the lands 126a from themember 114 enough to let the oil begin to leak past such lands. At thispoint it will be evident that the oil pressure will be just sufficientto bear the total thrust and will indicate the value of such thrust.Monitoring of such pressure through an opening in the surface 124a nearthe land 126a will thus constitute an accurate monitoring of the thrustforces. 1

In the structure of FIG. 7 the action is similar, rotation building uppressure over the surfaces 127 until pressure of the oil is great enoughto take the entire thrust force and separate the lands 12711 from themember 114.

In the Kingsbury bearing of FIG. 8 the effect is also similar. However,when the oil is swept by member 114 onto the leading edge of the shoe,its pressure lifts the leading edge away from member 114 and forms awedge-shaped body of oil with the leading edge thicker than thefollowing, but with both edges spaced from member 114 by the body ofoil. Monitoring this pressure through passageway 228 will serve tomonitor the thrust taken by the bearing.

Finally, in the Whipple bearing of FIGS. 9 and 10, the rotation ofmember 114 serves to sweep oil along grooves 324 from a part (radiallyinnermost) of larger cross section to a part of smaller cross sectionand build up pressure in the oil due to the drag of member 114 thereoveruntil it is sufficient to begin to separate the lands 325 from themember 114, permitting the oil to spread over the lands and begin toleak out past the outer margins of the facing thrust bearing members.Monitoring the pressure anywhere within this pressurized area butpreferably near the outer end of a groove 324 by the passageway 328 thenserves to monitor the thrust force. It will be understood that in any ofthe forms illustrated in all the FIGS; either member could be therotating member and the other the stationary member, that the grooves324 may open in either radial direction, and that the pressure sensingtap may open to any portion of the body of oil whose pressure keeps thebearing faces separate.

Thus the monitoring and control of thrust according to this invention isapplicable to the various hydrodynamic bearings as disclosed in the textof my original application, Ser. No. 1,130 as well as to the hydrostaticbearings disclosed therein.

It is to be noted that in the case of opposed bearings as illustrated inFIG. 1, in which there may be insuffi cient tolerance for endwisemovement of the shaft to relieve the oil pressure in one of the bearingsas that in the other bearing builds up under thrust. it is desirable tomonitor the differential between the pressures in the two bearings as atrue indicator of the thrust. However, if there is only one thrustbearing or the pressure on one is zero or negligible, it is unnecessaryto monitor any bearing except that taking the thrust. The arrangementfor monitoring the differential as shown is still desirable howeverbecause this not only provides a reference pressure for the bearingunder stress, but also allows monitoring the pressure of either bearingwhich may be under stress. 7

Clearly, the monitoring means in any of the forms of bearings disclosedmay be used to control a thrust controlling arrangement as shown in FIG.1.

Whereas, I have said that the pressure in the bearing is a measure ofthe thrust force or load supported by the bearing, the relation betweenthe measured pres sure and the thrust is not necessarily linear;peculiarities of the bearing configuration and of fluid flow behavior init may cause minor variations. However, it will be apparent that anypressuring measuring device used can be modified so as to compensate forsuch variations.

The methods and combinations described herein can be applied to anyrotating machinery having appropoiate thrust bearing or like assemblies.More generally, however, the methods and combinations will be applied tohigh speed rotating machinery such as centrifugal pumps and compressorsof both the single stage and multistage variety, turbines andturboexpanders also of the single stage and multistage variety.

I claim:

1. The method of controlling the axial thrust on a thrust bearingassembly of a rotating machine wherein said thrust bearing assemblycomprises a rotating component and a non-rotating component, one face ofsaid rotating component and one face of said non-rotating componentbeing in opposing relationship with each other, wherein a lubricant isforced in operation between the opposed faces of said components forminga first zone of pressure between said faces maintaining them separatedand transmitting thrust load between 11 them; and wherein there is abalancing means operable to apply a desired end thrust to one of saidcomponents to adjust the thrust forces onv said b caring'. said methodcomprising the steps ofdetermining from time to time the axial thrust onsaid assembly by monitoring the pressure of said lubricant in said firstzone and operating said balancing means in accordance with the axialthrust determination to produce a desired aggregate thrust on saidbearing assembly.

j 2. In a rotating machine having a thrust bearing assembly, saidbearing assembly having a rotating component an d a non-rotatingcomponent, one face of said non-rotating component and one face of saidrotating component being in opposing relationship with each other,wherein a lubrieant is forced in operation between the opposed faces ofsaid components forming a first zoneof pressure which is between saidfaces, and is pressurized to a thrust sustaining pressure to maintainsaid components'separated, and a second pressure zone is created in saidlubricant differing from said thrust sustaining pressure by an'a'mountindicative of the thrust on said bearing assembly; the improvement whichco'r npri s'es a pressure determining meansincluding pressuresensing: means exposed to saidfirst zone, a pressure'sensing meansexposed to said second zone, means 'for "'cor nparing" the two; and abalancing meanse rab1e'to' adjust to: desired value,"as indicated bysaid pressure determining means, the aggreg'ate'thiustforcie on saidbearing assembly. 31The combination of claim 2 wherein said balancingmeans is r'espons'ive'ly connected to said pressure determiningme'a'ns'and said pressure determining means contains means toautomatically adjust said balancing means. I

'4. The combination bf claim 2 wherein said rotating component of saidmachine is mounted on a shaft, wherein said' machine further comprises arotor mountedo'n said shaft distalsa'id bearing assembly and r 12 sureof saidlubricant in the other of said zones, determining the differencebetween the twoj pressu'res as an indication of the axial thrust on saidassembly, and adjusting 'said'balancing means in 'accordance with thewith one another, wherein a lubricant is forced into" said assembly andthen flows radially outwardbetween the mated faces of said rotating andsaid fixed compodesigned to pass'a working fluid therethrbugh a fixedmember between said rotor and said bearing'assembly, wherein aportion"of'-'said working fluid is allowed to leak into a space betweensaid rotor ands ai d fixed member, and wherein said balancingrn'eanscomprises means for controlling the pressure of th'e'working fluidinsaid'space. I L 5. A rotatingm'achi'neaccording to claim 2' whereinsaid second zone'is-loc'at'ed downstream from between the mated faces.

' 6. The method of controlling the axial thrust on a thrust bearingassembly in a rotating machine in'which machine said bearing assemblyhas a rotating component' and a fixed component,'one face of said'fixedcomponent andone face of said rotating component beingin opposed matingrelationship'with one another, andIin which machine a lubricant isforced into said assembly by the relative rotation of saidcomponents-and them flows between the mated faces of said rotating andsaidfixedrcomponent, and the flowof lubricantbetween-said mated facesgenerates zones of pressure, one of which is between said mated faces,sufficient to maintain said components separated, and the' pressure ofsaid zones differing from each other by an amountnent, the flow oflubricant radially outward between said matedfaces generating zones ofpressuresufficient to maintain said componentsiseparated, and thedifference in pressure of said zones being indicative of thevalue of thethrust load{ the improvement which comprises the combination therewithof a pressure measuring means connected so as to monitor the pressuregraclient of said lubricant across said mated faces between successiveonesvof such zones, at least one of which is between said mated facesand a balancing meansto adjust thethrust force on saidbearing assembly.v

9. The combination of claim 8 wherein saidbalancing means isresponsivelyconnected-to said pressure measuring means to automatically adjust saidbalancing means.-

10. In a rotating machine having a pair of opposing thrust bearingassemblies totmaintain axial location of a shaft of said machine, eachof said bearing assemblies having a rotating component mounted on saidshaft and anon-rotating component, :one face of said rotating componentand one;face of said non-rotating component being inn-opposingvrelationship. with eachother}, wherein a bearing lubricant bodyiscreated, in operation between the opposed facesof said components andmaintained under pressure sufficientto keep-said com,- ponents separatedand transmit, any thrust .forces ,between -them,the combination of avdifferential pressure measuring device connected -so:as tomeasure-,the-differel nee between thepressure of .saidlubrica'nt betweenthe opposed faces of one of said bearing assemblies and the pressureof'said' lubricantbetween the opposed faces-of the-other saidbearingassemblies, whereby when said rotating-components are displacedtin-oneedirectionby an end thrust lo'ading o'ne of said: bearing-assemblies andunloading the other, said comparison will indicate the pressure inthe'loaded assemblycom'pared to-an unloaded assembly and hence theendxthrust'on the loaded assembly, and abalancing meansto adjust thethrust force on said bearing assemblies.-

11. The combination of claim 10 wherein said balancing means is'responsively connected'to said-differential pressure measuring meansand'said differential pressure-measuring means contains means toautomatically adjust said'balancingmeansa i 12; A rotating machineaccording to claim 10 whereinthe lubricant between each of the opposedbearing assembliesforms part of a commonlubricant body.

* l3. rotating machine according to claim 10 wherein said bearinglubricant bodies are created by the relative rotation of saidcomponents.

1. The method of controlling the axial thrust on a thrust bearingassembly of a rotating machine wherein said thrust bearing assemblycomprises a rotating component and a nonrotating component, one face ofsaid rotating component and one face of said non-rotating componentbeing in opposing relationship with each other, wherein a lubricant isforced in operation between the opposed faces of said components forminga first zone of pressure between said faces maintaining them separatedand transmitting thrust load between them; and wherein there is abalancing means operable to apply a desired end thrust to one of saidcomponents to adjust the thrust forces on said bearing; said methodcomprising the steps of determining from time to time the axial thruston said assembly by monitoring the pressure of said lubricant in saidfirst zone and operating said balancing means in accordance with theaxial thrust determination to produce a desired aggregate thrust on saidbearing assembly.
 2. In a rotating machine having a thrust bearingassembly, said bearing assembly having a rotating component and anon-rotating component, one face of said non-rotating component and oneface of said rotating component being in opposing relationship with eachother, wherein a lubricant is forced in operation between the opposedfaces of said components forming a first zone of pressure which isbetween said faces, and is pressurized to a thrust sustaining pressureto maintain said components separated, and a second pressure zone iscreated in said lubricant differing from said thrust sustaining pressureby an amount indicative of the thrust on said bearing assembly; theimprovement which comprises a pressure determining means including apressure sensing means exposed to said first zone, a pressure sensingmeans exposed to said second zone, and means for comparing the two, anda balancing means operable to adjust to a desired value, as indicated bysaid pressure determining means, the aggregate thrust force on saidbearing assembly.
 3. The combination of claim 2 wherein said balancingmeans is responsively connected to said pressure determining means andsaid pressure determining means contains means to automatically adjustsaid balancing means.
 4. The combination of claim 2 wherein saidrotating component of said machine is mounted on a shaft, wherein saidmachine further comprises a rotor mounted on said shaft distal saidbearing assembly and designed to pass a working fluid therethrough and afixed member between said rotor and said bearing assembly, wherein aportion of said working fluid is allowed to leak into a space betweensaid rotor and said fixed member, and wherein said balancing meanscomprises means for controlling the pressure of the working fluid insaid space.
 5. A rotating machine according to claim 2 wherein saidsecond zone is located downstream from between the mated faces.
 6. Themethod of controlling the axial thrust on a thrust bearing assembly in arotating machine in which machine said bearing assembly has a rotatingcomponent and a fixed component, one face of said fixed component andone face of said rotating component being in opposed mating relationshipwith one another, and in which machine a lubricant is forced into saidassembly by the relative rotation of said components and them flowsbetween the mated faces of said rotating and said fixed component, andthe flow of lubricant between said mated faces generates zones ofpressure, one of which is between said mated faces, sufficient tomaintain said components separated, and the pressure of said zonesdiffering from each other by an amount indicative of the Value of thethrust load, said machine having in addition to a balancing means toadjust the thrust force on said bearing assembly; said method comprisingthe steps of monitoring the pressure of said lubricant in said one ofsaid zones, monitoring the pressure of said lubricant in the other ofsaid zones, determining the difference between the two pressures as anindication of the axial thrust on said assembly, and adjusting saidbalancing means in accordance with the axial thrust indication.
 7. Themethod of claim 6 wherein said other of said zones is a zone of constantpressure of said lubricant.
 8. In a rotating machine having a thrustbearing assembly having a rotating component and a fixed component, oneface of said fixed component and one face of said rotating componentbeing in mating relationship with one another, wherein a lubricant isforced into said assembly and then flows radially outward between themated faces of said rotating and said fixed component, the flow oflubricant radially outward between said mated faces generating zones ofpressure sufficient to maintain said components separated, and thedifference in pressure of said zones being indicative of the value ofthe thrust load; the improvement which comprises the combinationtherewith of a pressure measuring means connected so as to monitor thepressure gradient of said lubricant across said mated faces betweensuccessive ones of such zones, at least one of which is between saidmated faces and a balancing means to adjust the thrust force on saidbearing assembly.
 9. The combination of claim 8 wherein said balancingmeans is responsively connected to said pressure measuring means toautomatically adjust said balancing means.
 10. In a rotating machinehaving a pair of opposing thrust bearing assemblies to maintain axiallocation of a shaft of said machine, each of said bearing assemblieshaving a rotating component mounted on said shaft and a non-rotatingcomponent, one face of said rotating component and one face of saidnon-rotating component being in opposing relationship with each other,wherein a bearing lubricant body is created in operation between theopposed faces of said components and maintained under pressuresufficient to keep said components separated and transmit any thrustforces between them, the combination of a differential pressuremeasuring device connected so as to measure the difference between thepressure of said lubricant between the opposed faces of one of saidbearing assemblies and the pressure of said lubricant between theopposed faces of the other said bearing assemblies, whereby when saidrotating components are displaced in one direction by an end thrustloading one of said bearing assemblies and unloading the other, saidcomparison will indicate the pressure in the loaded assembly compared toan unloaded assembly and hence the end thrust on the loaded assembly,and a balancing means to adjust the thrust force on said bearingassemblies.
 11. The combination of claim 10 wherein said balancing meansis responsively connected to said differential pressure measuring meansand said differential pressure measuring means contains means toautomatically adjust said balancing means.
 12. A rotating machineaccording to claim 10 wherein the lubricant between each of the opposedbearing assemblies forms part of a common lubricant body.
 13. A rotatingmachine according to claim 10 wherein said bearing lubricant bodies arecreated by the relative rotation of said components.